Building construction.



UNITED sTATEsrATENT orrrcn.

JULIUS KAHN, OF DETROIT, MICHIGAN, ASSIGNOR TO TRUSSED CONCRETE STEELCOMPANY, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

BUILDING CONSTRUCTION.

- Specification of Iietters Patent.

Patented Feb. 8, 1910.

Application led January 11, 1909., .Serial No. 471,67L

proved Building Construction, of which the following is a specification.

My invention relates to reinforced concrete construction, particularlyto beams and floor slabs which are intended to carry great weights, andits object is to provide a reinforcement` for such construction sodesigned that maximum strength will be obtained for weight of metal.

My invention consists in a rolled beam which has the general shape of anI beam, with its lowerh flange of greater area 'than its upper, and itsweb tapering upward in thickness; which beam is slitted so that it maybe expanded, forming a part-truss in which the upper tension membersgradually increase toward the ends, the lower tension member graduallydecreases toward the ends,`and the inclined shear' members are ofincreasing thickness toward the ends.

In the accompanying drawings Figure 1 is A-a vertical cross section of acomposite beam showing my improved tension member in position. Fig. 2shows one end of the tension member on a larger scale after beingslitted ready for expansion. Fig. 3 is an end view of a tension member,the figure being provided with a series of horizontal lines to indicatewhere the member will be slitted.

Similar reference characters refer to like parts throughout-the severalviewst The reinforcements of concrete beams are usually badly designedand as a result much metal is wasted.' The main tension member lying inthe bottom of a beam should be of maximum strength at the middleof thebeam and need have little strength at the ends of the beam. But theJusual practice is to employ reinforcing members of the same crosslsectional area throughout their length. Where continuous beams extendacross columns, those portions in each side of the columns act ascantalivers and must be reinforced accordingly. The tension membersnearest the upper surface must have greatest strength at the columns, asthe stresses decrease toward the center of the beam. As the shear in thebeam increases in proportion to the distance from the center of the beamit is also necessary that the auxiliary memberspf the reinforcement forconcrete construction, Wh1ch are to resist this'shear, should alsoincrease 1n strength in propor- .tion to their distance from the centerof the beam.

In the construction shown in the drawing the requirements set forthabove have been practically met. The structural beam. 1,

which is of peculiar shape generally resembling .an I beam, has an upperflange 2 and lower tlange. This upper flange may vary from the sizeshown in dotted lines to that shown in 'solid lines, but is seldom madelarger. The webincrea'ses in thickness toward the bottom. .This 'beam isformed with a series ofhorizontal slits L which overlap each other andis then expanded as shown in Fig: 1. It has been found that this crosssection meets approximately a greater number of problems Aand istherefore the most desirable merchantable form.

Fig. 1 shows continuous beams of concrete 5 extending over supports Gand 7. The tension member 8 in the lower portion of the beam hasintegral with it the inclined shear members 9, 10,11. 12 and 13 which inturn unite to the upper longitudinal tension members 14. The-members 14of the adjacent span may merely overlap, be integral or connected infanydesired manner as by plates 15. 'It will b e noticed that the inclinedshear members `10, 11, 12 and 13 increase in cross sectional area fromthe center of the beam and decrease from the supports, that the tensionmember 8 in the bottom of the beam decreases toward the ends of the beamand that the reinforcements 14 in the cantalivers decrease toward theends of the canta/livers.` The distance between the points-of theattachment of the members 9 to the main tension member 8 Will depend uon the beam whichisto be reinforced andi main portion`8 and inclinedmembers 9, 10, l1, 12 and 13. These Will extend upward in the usualmanner as shown in Fig. l.. The rule of increasing size for equallyspaced shear members Will be met Witlrthis construction. Any desirednumber of shear members can be formed from the metal shown in thedrawings.y

Having now explained my improvements what I claim as my invention anddesire to secure by Letters Patent is 1. An expanded metal constructioncomprising outer members extending parallel to each otherv and connectedby a plurality of tie pieces, the entire structure made of a singlepiece of metal and the tie pieces on each side of, the center beingparallel to each other and increasing in cross sectional area from thecenter all the parts being in the same plane.

2. An expanded metal construction comprising members extending parallelto each other and connected pieces which gradually increase 1n crosssectional area, the entire structure made of a single piece of metal andlying in the same plane. I

k3. An expanded metal construction comprising a lower tension member,upper tension members parallel to the lower member at its ends, anddiagonal tie members extending between the lower tension member and theupper tension members, the tie members connected'V to each uppertensionV member being parallel to each other, the lower tension memberdecreasing in cross sectional area toward its ends, all the membersbeing integral and in the same plane.

4. An expanded metal construction comprising amain tension memberdecreasing in size toward its ends,

additional tension members parallel to the mam tension membya pluralityof tiel web tapering upward and having ber and increasing in size inproportion to the decrease of the main tension member, diagonal membersconnecting the main tension member to each of the other tension in thesame plane.

5. An expanded' metal construction comprising a main tension memberdecreasing in size toward its ends, its middle portion being in the formof an I beam having its the lower flanges of the greater cross-sectionalarea than the upper inclined shear members integral with the mainmember, and increasing in cross-sectional area from the center andadditional tensional members parallel vto the ends of the main memberand connected thereto by the shear members.

members "and integral therewith and lying 6. An expanded metal structureconsistp ing of one main member and two auxiliary members parallel tothe ends of the main member and in -line with each ether, the auxiliarymembers increasing and the main member decreasing in size toward theirouter endsLand ties extending between the main member and the auxiliarymembers` and integral with the same all the parts bein the same plane.

7. An expanded metal structure consisting of three member' allin thesame plane, two members being parallel to the third and in line vvgitheach other, the third member decreasing in size toward its ends, andties between the members and integral therewith all the parts being inthe same plane.

In testimony whereof, I have signed this speciiication in the presenceof two subscribing witnesses.

JULUS KAHN. Witnesses:

MINNIE K. KENNEDY, EDWARD N. PAGELSEN.

